Dan, there are sometimes large costs involved here that you might want to check out first.
What you call "cleaning" is called "Trash-Out" by REALTORS, so you might want to google that term and the word Minnesota and see what you find.
My husband was considering doing this too, but he decided against it because of the possibility of handling hazardous materials and the costs involved.
To be best of my knowledge, you do not have to be licensed to pick up "normal" garbage, but then what do you do with it? You DO have to be licensed to do certain kinds of Trash Hauling and Disposal. In other words, once you clean out the house, how you handle the trash is critical? That can be VERY costly and require multiple licenses.
Another consideration is what kind of trash is it? If you have chemicals, batteries, used oil, flourscent light bulbs, paint, electronics equipment, etc. these are considered hazardous and need special handling. Hazmat handling gets expensive fast.
You will need to be insured and bonded, or most REALTORS will not want to work with you.
Minor repairs may be needed, but are not generally considered to be part of a "trash out".
You might consider working for a trash-out company for a while to learn the ropes and see if you even like doing it. Maybe check out someone like JJO Enterprises in Andover.
Starting a new business is a big risk. Please check with the Minnesota Secretary of State office to find out more about hazmat disposal and handling, trash hauling, and trash disposal licenses and fees.